The Legend of Zelda: Majora's Mask went through a lot of changes while in development, and that included the removal of a mask that was so strong, it broke the game. Since the Nintendo 64 had limited hardware capabilities compared to modern consoles, the developers had to decide what to cut and what to keep.
The development team for Majora's Mask faced more issues than a mask that was too strong to reasonably include. With one year to create the game, the developers expressed their frustrations through the words of Termina residents, which would be the origin of the iconic terrible fate quote in Majora's Mask. However, the original form of the Fierce Deity Mask needed to be redone because including it in the game would have made it too easy, even if the team was working on limited time.
The Strongest Mask In Majora's Mask Never Made It Into The Final Version
The Fierce Deity Mask and Giant's Mask are the final versions of the masks that originated from the mask that broke Majora's Mask during game tests. Since the mask once combined the powers of the resulting masks, players might be able to see how it could have been game-breaking if it was included in the final version of Majora's Mask. However, the combined abilities of Fierce Deity and Giant's Mask might not have been the most overpowered aspect of the original.
How The Original Mask Broke Majora's Mask
One of the few Legend of Zelda games not set in Hyrule, Link was able to use the original mask anywhere in Termina. This allowed players to have the strength of the Fierce Deity Mask combined with the size of the Giant's Mask to fight against any enemy in Majora's Mask. This trait might have ultimately been what got the mask removed from the game, and its abilities split between the Fierce Deity Mask and Giant's Mask, which were also limited to being used in the boss rooms that required them.
Many players might consider Majora's Mask as the strangest game in the Zelda franchise, but the issues and time restraints that the developers faced can make it seem impressive that the game made it to release. Taking the time to change a single mask was necessary, however, since it could have made even the Zelda Great Fairies in Majora's Mask obsolete as their upgrades wouldn't have been needed to help players. While the Fierce Deity Mask and Giant's Mask are still useful for players, it could have been fun to play the original mask that broke The Legend of Zelda: Majora's Mask.
Source: DidYouKnowGaming?/YouTube